Sanitary processing pumps



Dec. 2, 1969 B. A. WERRA 3,481,273

SANITARY PROCESSING PUMPS Filed Feb. 26, 1968 INVENTOR BRUNO H. WERRAATTORNEYS United States Patent 3,481,273 SANITARY PROCESSING PUMPS BrunoH. Werra, Waukesha, Wis., assignor to Ladish C0., Cudahy, Wis., acorporation of Wisconsin Filed Feb. 26, 1968, Ser. No. 708,117 Int. Cl.F04d 1/00; F04b 21/00; F16j 15/42 US. Cl. 103-103 9 Claims ABSTRACT OFTHE DISCLOSURE The hub of the impeller of a liquid pump, as well as aportion of the impeller shaft therebelow, rotate in a pocket in the baseof the pump housing and are provided with circumferentially spacedgrooves which are angled in a direction to cause flushing of the pocketand adjacent parts when the pump is in operation.

BACKGROUND OF THE INVENTION Field of the invention The present inventionrelates to liquid processing equip ment, and more particularly to anovel self-cleaning impeller hub arrangement for use in liquid foodpumps and similar equipment having a pocket in which the impeller hu-brotates.

Description of the prior art In milk blending pumps and other liquidfood processing equipment it is necessary to thoroughly clean andsanitize said equipment at frequent regular intervals. Ordinarily theequipment is cleaned in place immediately after each processingoperation with caustics, acids and sanitizers at elevated temperatures.In certain pumps, such as electrically-driven blending pumps,power-driven impeller assemblies have a recessed hub-receiving pocketand crevices between adjacent parts in the bottom of the pump housingwithin which milk or other matter becomes trapped and accumulates. Withconventional arrangements said accumulated residue is not thoroughlyflushed out from the crevices and pockets during the cleaning operation,with the result that subsequent food batches introduced into theprocessing pump may become contaminated thereby. This is not tolerablein the dairy and other liquid food processing industries wherein highsanitation standards must be rigidly maintained.

SUMMARY OF THE INVENTION The present invention provides an improved pumpassembly for use in liquid food processing equipment and the likewherein the impeller hub and drive shaft are provided with novelcirculation-creating means in the form of angularly-disposed,circumferentially-spaced grooves which function to forcibly flush thehub pocket. The result is that such pocket and adjacent parts areeffectively purged, thereby promoting the complete sanitization of thedevice. I

Further objects of the present invention are to provide a novelself-cleaning impeller assembly for sanitary processing pumps or thelike which is simple in design and operation, which is reliable in use,and which is otherwise patricularly well adapted for its intendedpurposes.

Brief description of the drawing In the accompanying drawing, whereinthe same reference numerals designate the same parts in all of theviews:

FIG. 1 is a side elevational and partial vertical sectional view of aprocessing pump connected to the bottom of a liquid tank;

FIG. 2 is a top plan view of the stub shaft featured in the invention;and

3,481,273 Patented Dec. 2, 1969 FIG. 3 is a top plan view of theimpeller with the upper end of the stub shaft fitted in the impelleropening.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now more particulalryto FIG. 1 of the drawing, the numeral 10 designates a tank or containerof the type commonly used in dairies in conjunction with a milkprocessing pump, the pump housing 11 being mounted below and having atop opening communicating with a bottom opening 9 of said container, asshown. As is usually required in the dairy and food processing industry,said tank 10 and pump housing 11 are formed of stainless steel orequally corrosion resistant material,

as are all of the other structural components hereinafter described, inorder to provide maximum sanitation.

The pump housing 11 is generally cylindrical in form and has a dischargeopening 12 in one side thereof to which a conduit or the like can beattached. Said pump unit is mounted on a suitable support or adapter 13above or adjacent to an electric motor 14, there being a clamping ring15 or the like securing the pump housing in position on the support 13.Projecting upwardly or outwardly from the motor is a drive shaft 16.Fitted over the upper or outer end of said drive shaft 16 is a stubshaft 17, there being suitable slot and interfitting key means 18, 18drivably connecting said stub shaft 17 to said drive shaft.

Referring still to FIG. 1, the stub shaft 17 includes an intermediateportion 21 of reduced diameter, and projecting thereabove is a portion23 of still smaller diameter, the latter portion being rotatablyjoumaled in an opening in the bottom of the plate 26.

Surrounding the intermediate portion 21 of the stub shaft is a coilspring 22 which bears against the underside of an annular cup-shapedretainer 25 for a carbonring 24, there being a rubber O-ring 24 withinthe carbon ring. This provides a seal around said stub shaft and thecarbon ring is urged upwardly by the spring 22 into sealing engagementwith the underside of the bottom plate 26 of the pump housing. Saidbottom plate 26 has a central pocket 26 to accommodate the hub of theimpeller, as will be described hereinafter, and the opening within whichthe stub shaft portion 23 is journaled is formed in the bottom of saidpocket 26'. As will be hereinafter described in greater detail, pumpingmeans such as a plurality of circumferentially spaced, angled grooves 29are formed in the periphery of said stub shaft portion 23, said groovesextending upwardly at an angle from a point immediately above theaforementioned O-ring 24 and communicating with the shoulder 40 at thetop of said shaft portion 23 (see FIG. 2.). Four of said grooves 29 areused in the illustrated embodiment of the invention, but the inventionis not to be limited in this respect.

Formed integrally with and projecting upwardly from the stub shaftportion 23 is an upper stub shaft portion 27 of less size and whichprojects into the interior of pump housing 11. As best appears in FIG.2, said upwardly-projecting stub shaft portion 27 is substantiallysquare in cross section and has beveled corners as at 28. Theaforementioned grooves 29 in the stub portion 23 open immediatelyadjacent the lower ends of said beveled corners, the function of whichwill be hereafter seen.

Fitted on the squared uppermost portion 27 of the stub shaft 17, andseated on the shoulder 40 provided by the enlarged stub shaft portion 23therebelow, is the hub 31 of the impeller 34, the aforementioned pocket26' in the bottom 26 of the pump housing being of greater diameter thansaid hub to loosely accommodate it. Said impeller hub 31 has a squareopening 32 (FIG. 3) adapted to receive the squared stub shaft portion27, there being vertical passageways 41 adjacent the beveled corners 28.Suitable means, such as the transverse pin 30, insertable into a bore inthe upper end of the stub shaft portion 27 removably retains theimpeller in assembled position.

As is apparent from the above, when the impeller is driven by the motor14- the lower portion of the hub is rotated in the pocket 26.

As is shown in FIGS. 1 and 3 of the drawing, the periphery of theimpeller hub 31 is provided with pumping means such ascircumferentially-spaced, angularly-disposed grooves 33, the purpose ofwhich will be hereinafter described.

The blades of the impeller 34 project from the upper portion only of thehub 31. Said blades are shaped to carry out the mixing or propellingaction of the processing pump, as is well known in the art. Theabove-described angular hub grooves 33 communicate with the top of thehub, as shown, there being, in the illustrated embodiment, three of saidgrooves, one between each pair of impeller blades. Preferably, saidgrooves 33 are disposed at an angle of about 55 from the horizontal.

In the operation of a milk processing pump of the type illustrated, milkin the tank fills the pump housing 11, and when the motor is operated todrive the shaft 16 and stub shaft 17, the impeller 34 is rotated to mix,blend, or move said milk as desired.

As heretofore mentioned, in conventional processing pumps a quantity ofthe milk or other liquid being processed finds its way into the pocket26' in the bottom 26 of the pump housing, and into any adjacent crevicesand between the stub shaft 17 and the impeller hub 31. After the milk isdrained from the system there are trapped milk particles and semisolidsforming a residue coating which is difficult to flush out when theapparatus is periodically flushed with cleaning solution, with theresult that said food particles accumulate and may contaminatesubsequent batches of milk or other liquid product introduced into saidunit.

In addition, in conventional pumps caustic sanitizers used in the flushcleaning of said blending apparatus may remain in the pocket 26 and increvices between adjacent parts and this is obviously undesirable. It isto eliminate the accumulation of such contaminating matter from thepockets and crevices in the pump housing that the novel hub and stubshaft grooves 33 and 29 are provided.

As viewed in FIGS. 2 and 3 of the drawing, the stub shaft portion 17 andinterconnected impeller hub 31 are designed to rotate in acounterclockwise direction, as indicated by the directional arrows inFIG. 3, and the angled grooves 33 and 29 in said members are biasedupwardly and rearwardly relative to said direction of rotation. As aresult, when said impeller and stub shaft assembly is rotated during useas well as during a flushing operation said grooves act as pumps toflush out any milk particles or other residue from the adjacent pocketand crevices, said matter being urged upwardly in said angled groovesand being discharged from the tops of said grooves into the housing 11,where the material is evacuated through the discharge opening 12 by theflushing solution. The result is that during normal use milk is alwayskept agitated in the pocket 26' so there is less likelihood of itcollecting in hardened form. Also when the system is being flushed witha cleaning solution the pocket 26' and crevices between adjacent partsare effectively purged of any contaminating matter which may haveremained after draining, and the complete sanitization of said unit ispromoted.

In addition to the accumulation of foreign matter in the impeller hubcavity 26', it has been found that in conventional pumps milk pariclesor other foreign matter find their way into the impeller hub opening 32.The corners 28 of the stub shaft portion 27 are beveled, therebycreating corner recesses 41 within which food particles and the like canaccumulate. The arrangement of the angular grooves 29 with their upperends opening immediately adjacent said beveled shaft corners 28,however, as

shown in FIG. 2, results in direct communication between saidcirculation-creating grooves and the corners 41, and any food or thelike accumulated therein is effectively flushed from the hub opening,and there is also agitation near the hole for the retainer pin 32.

From the foregoing detailed description it will be seen that the presentinvention provides a novel and improved impeller assembly for use insanitary blending or processing pumps and the like which is designed toprevent food or other matter from being trapped and accumulating inpockets and crevices in said pump, and possibly contaminating subsequentfood products introduced therein. Said novel, self-cleaning pumpassembly is simple in design and operation, is reliable in use, and isotherwise particularly well adapted for its intended purposes.

It is to be understood that while the present invention has beendescribed herein as being particularly well suited for use in a milkblending or processing pump of the type commonly used in dairies, theimproved sanitary pump assembly featured in the present invention canalso be advantageously utilized in other types of liquid processingequipment, as well as in pumps used in other industries where a similarproblem is present. It is to be understood, too, that while a preferredembodiment of the present invention has been illustrated and describedherein, variations or modified forms thereof may occur to those skilledin the art. For example, the object of the invention may be accomplishedeither by the grooves 29 or by the grooves 33, but by having both setsof grooves the action is more efficient. Also the invention is useful ineither vertically or horizontally disposed pumps. What is intended to becovered herein is not only the illustrated embodiment of the inventionbut also any and all variations or modifications thereof as may comewithin the spirit of said invention, and within the scope of thefollowing claims.

What I claim is:

1. In a liquid pump having a housing with a wall portion provided with apocket, said pocket having a cylindrical wall and having a bottom, andsaid pump having an impeller mounted for rotation in said housing, saidimpeller including a hub having a cylindrical wall and having inner andouter end faces, the inner portion of said cylindrical wall of said huband said inner end face being disposed in said pocket and anotherportion of said cylindrical wall projecting outwardly of the pocket andterminating in said outer end face, said impeller including bladessupported by only the said portion of the hub which projects outwardlyof the pocket, said cylindrical wall of the hub having a plurality ofcircumferentially spaced grooves extending at an oblique angle but in agenerally axial direction with respect to the hub, a portion of thelength of said grooves being out of the pocket and said grooves servingas pumping means positioned to act on liquid in the pocket to causeflushing thereof and adjacent parts when the impeller is rotated.

2. A liquid pump as claimed in claim 1 in which the hub is integral withthe impeller.

3. A liquid pump as claimed in claim 1 in which the angled grooves havetheir lower ends communicating with the lower face of said hub portionwithin the pocket.

4. In a liquid pump having a housing with a wall portion provided with apocket and having an impeller mounted for rotation in said housing, saidimpeller having a hub, and there being a drive shaft for the impeller,the improvement comprising rotatable parts in said pocket connected tosaid impeller for rotation therewith and including both a portion of thedrive shaft for the impeller and the hub portion of the impeller, eachof said portions having pumping means thereon positioned to act onliquid in said pocket to cause flushing of the pocket and adjacent partswhen the impeller is rotated.

5. Apparatus as claimed in claim 4 in which the pumping means on each ofsaid parts comprises circumferentially spaced angled grooves.

6. In a liquid pump having a housing with a wall portion provided with apocket and having an impeller mounted for rotation in said housing, adrive shaft for the impeller which projects through said pocket andwhich has a rotatable part in said pocket having pumping means thereonpositioned to act on liquid in said pocket to cause flushing of thepocket and adjacent parts when the impeller is rotated, the impeller endof the drive shaft being reduced and squared, and said impeller having asquare hole to receive said squared end of the drive 10 shaft, and therebeing a shoulder between said part of the drive shaft which rotates inthe pocket and the squared upper end of the drive shaft, which shoulderis located in the pocket, the pumping means being positioned to directliquid into the hole of the impeller.

7. A liquid pump as claimed in claim 6 in which the pumping meanscomprises peripherally spaced angled grooves having upper ends at saidshoulder to direct liquid into the hole of the impeller.

8. Apparatus as claimed in claim 6 in which the corners of the squaredupper end of the drive shaft are beveled to provide corner passageways,and in which the pumping means is located at the lower ends of saidpassageways to flush the same,

9. Apparatus as claimed in claim 8 in which the pumping means is in theform of peripherally spaced angled grooves whose upper ends are locatedat the lower ends of the corner passageways.

References Cited UNITED STATES PATENTS 823,077 6/ 1906 Pitman. 1,504,6588/1924 Ulmer. 1,791,547 2/1931 Yoder. 2,669,938 2/1954 LaBoor 103-115FOREIGN PATENTS 618,598 12/ 1926 France. 325,930 3/1930 Great Britain.312,362 2/ 1956 Switzerland.

HENRY F. RADUAZO, Primary Examiner U.S. Cl. X.R.

